Summary information and primary citation

PDB-id
1n32; SNAP-derived features in text and JSON formats; DNAproDB
Class
ribosome
Method
X-ray (3.0 Å)
Summary
Structure of the thermus thermophilus 30s ribosomal subunit bound to codon and near-cognate transfer RNA anticodon stem-loop mismatched at the first codon position at the a site with paromomycin
Reference
Ogle JM, Murphy IV FV, Tarry MJ, Ramakrishnan V (2002): "Selection of tRNA by the Ribosome Requires a Transition from an Open to a Closed Form." Cell(Cambridge,Mass.), 111, 721-732. doi: 10.1016/S0092-8674(02)01086-3.
Abstract
A structural and mechanistic explanation for the selection of tRNAs by the ribosome has been elusive. Here, we report crystal structures of the 30S ribosomal subunit with codon and near-cognate tRNA anticodon stem loops bound at the decoding center and compare affinities of equivalent complexes in solution. In ribosomal interactions with near-cognate tRNA, deviation from Watson-Crick geometry results in uncompensated desolvation of hydrogen-bonding partners at the codon-anticodon minor groove. As a result, the transition to a closed form of the 30S induced by cognate tRNA is unfavorable for near-cognate tRNA unless paromomycin induces part of the rearrangement. We conclude that stabilization of a closed 30S conformation is required for tRNA selection, and thereby structurally rationalize much previous data on translational fidelity.

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